Poltau

A novel polarisation-based detection approach for fluorescence lifetime imaging (FLIM) in laser scanning microscopes at lower cost, enabling broader use in cell biology, tissue imaging and drug discovery.​

Proposed Uses

PolTau provides an efficient, lower-cost means to implement frequency-domain detection in laser scanning FLIM microscopy, particularly suited to multiphoton systems, which are already widely adopted in biomedical research. The technology has applications in biomedical imaging with relevance to both cell biology and drug discovery, for example using FRET to assay molecular interactions. By combining with hyperspectral imaging, it can deliver detailed lifetime and spectral information in a single experiment, offering richer insight into cellular and tissue function.

Problem addressed

Current FLIM techniques are expensive and inefficient, relying on ultrafast detectors such as SPADs or photomultipliers in combination with time-correlated single photon counting (TCSPC). These approaches suffer from low quantum efficiency and relatively slow imaging speeds, limiting their accessibility and throughput. PolTau uses electro-optic modulators (EOMs) to provide time-resolved detection, offering a competitive cost and efficiency advantage. Prior attempts to use electro-optic modulators (EOMs) for FLIM have required challenging, custom-built components that reduce resolution and limit modulation frequency, providing only partial functionality.

Technology Overview

This invention realises laser-scanning phasor-based FLIM by directing the descanned fluorescence signal through a compact electro-optic modulator (EOM), synchronised to the excitation frequency. The design avoids birefringence-induced field-of-view limitations, reduces voltage requirements, and crucially eliminates the 50% signal loss typically caused by polarising beam splitters. By exploiting mature EOM technology, already widely deployed in telecommunications and laser modulation, the approach removes the need for ultrafast specialist detectors. Instead, it can be implemented with CMOS cameras, which routinely achieve 70–90% quantum efficiency thereby enhancing sensitivity while lowering cost. By supporting phasor analysis as well as the potential integration with hyperspectral imaging, the technique offers robust, versatile data collection. Overall, it offers a faster, more efficient, and more affordable FLIM solution.

Intellectual property information

UK priority patent application filed May 2025 GB2507609.2 – Optical Signal Processing

Benefits

Cost & Efficiency​

• Lower cost implementation of FLIM compared with conventional detector-based systems.​
• Reduced system complexity and improved efficiency by eliminating reliance on photomultipliers or fast photodiodes with low quantum efficiency (QE)​

Performance & Sensitivity​

• Higher sensitivity through use of CMOS cameras with higher QE (70–90%).​
• Faster imaging compared to sector gold-standard time-correlated single photon counting (TCSPC).​
• Direct phasor acquisition enables more complete representation of complex fluorescence decay profiles.​

Versatility & Applications​

• Potential integration with hyperspectral imaging, providing richer lifetime and spectral information in a single experiment.